Synchronous rectification replaces a traditional rectifier with a Field Effect Transistor (FET) switch. This reduces power dissipation as the forward voltage drop in the FET switch is much lower than the forward voltage drop of a rectifier. However, the reverse recovery time of the FET body diode in higher voltage applications (e.g. greater than about 60 Volts, >60V) is substantial. Therefore, switching losses can be quite high and the switching frequency of the power supply can be limited.
Most of the prior improvements addressing this problem have been driven by FET manufacturers. In the recent past, the reverse recovery time of the body diode in low voltage FET switches has improved significantly. However, the reverse recovery time of the body diode in high voltage FET switches still remains too high, causing extensive switching losses. One solution that tackles the extensive switching losses is to package a Schottky diode in parallel with the FET switch. However, this solution may not be effective for 100V to 200V applications since the forward drop of the FET body diode is comparable to the forward drop of the Schottky diode. Therefore, some current remains in the body diode when the FET is switched off, such that the FET switch still has a significant associated reverse recovery time, resulting in reduced, but intolerable switching losses.
It is with respect to these considerations and others that the disclosure made herein is presented.